Last truck I rented was Uhaul. Some of the Uhaul trucks are a little older, some a lot older, but generally they are good enough. Be very careful of the condition you return them in. And if you are at all concerned, get the insurance. The truck I rented was a perfectly good truck, and had no trouble with it. One annoyance was that they give it to you with 7/8 of a tank, and expect it back the same. But that's hard to measure, so they're gypping you on the gas some. Bring your digital camera, and document the condition of the truck if there's anything notably damaged on it when you pick it up. Make sure the rental office has a note of anything like that before you drive off the lot.
Other than the miscellenous fees being a whole lot larger of a part of the total price than you would probably expect, I had no problems with my experience. Although the time periods for the rentals can be pretty tight.